It is possible that the main title of the report Marfan Syndrome is not the name you expected. Please check the synonyms listing to find the alternate name(s) and disorder subdivision(s) covered by this report.
As Jenny points out, being able to lisp the alphabet song at age two has little to do with 'knowing' the alphabet. And, yes, most children learn the letters by sight and sound in kindergarten, although most are capable of learning this information sooner if diligently taught by parents or others.
Learning the letters of the alphabet is one of the first skills your child needs to develop in order to be able to read. Writing is an essential part of learning, but like anything else, kids' writing skills develop at different ages. The Scholastic website points out there is no need to worry if a child doesn't show interest in writing by age 3 1/2, as it will come in time. Not all children write as early as others do.